1. Field of the Invention
The present invention relates to an apparatus for displaying frequency distributions of measured values, or the like, over an adjustable measuring range wherein the measuring range is subdivided into sections of equal size and the sections are continuously numbered, whereby the number of measured values falling into each size class is stored and displayed and is capable of being read out.
2. Description of the Prior Art
An apparatus of the type generally set forth above has become known from the periodical "Electrical Engineering," 1978, Vol. 1, pp. 61-65. This apparatus serves the purpose of continuous monitoring of the pulse of human beings over long periods of time in order to be able to determine (or ascertain) cardiac rhythm malfunctions (or disturbances). It processes the signals derived from the pulse, according to the principle of frequency distribution, into a histogram (or stepped polygon). Since the absolute values of the chronological intervals of successive pulses are not of such great interest for the formation of the histogram, only the fluctuations of these values about a mean value are detected.
The classification proceeds according to the counting principle; i.e., a conversion of the quantity "time" into a digital quantity is carried out by means of counting out pulses of an oscillator. In the case of every measuring clock pulse, this quantity, stored in a counter, is transferred into a classification unit whose output information represents the respective class assignment, or address, respectively. The address ascertained by the classification unit is summed up in a class-wise fashion in a memory with the aid of a measuring clock pulse. The addition operation require several command steps which are executed in the memory by means of a sequence of pulses of a special sequence control. Furthermore, the known apparatus exhibits an addressing unit which activates the memory and an output matrix by way of addresses. The memory information can be rendered visible on a light-emitting diode display in the form of a histogram. Additions are possible from the memory until a maximum occupation (assignment) in a class occurs. Thereafter, additional classifications are blocked. As soon as such a blocking is present, the various programs can be activated. Therefore, a subtraction program can be triggered, whereby, in each of the classes, a reduction by one is effected, as long as at least one value was stored. In case the number of stored values was zero in advance, the subtraction operation does not take the place in the corresponding class. The corresponding histograms are thereby displaced "downwardly" by one location in the course of several subtractions.
In addition, with blockage of the memory as a consequence of an attained maximum occupation of a class, an automatic recorder output can be activated, whereby the histogram is read out on a synchronously-started recorder. Subsequently, the histogram is erased. In this manner, short-period histograms can be read in certain time intervals which permit inferences regarding the dynamics of the cardiac activity over longer periods of time.
An apparatus of this type can be introduced only to a limited degree in the technical field because a precise chronological, statistical distribution is not readily recognizable.